The present invention relates to a semiconductor memory device such as an EPROM in which stored information is erased by light irradiation such as an ultraviolet ray irradiation, and more particularly to a semiconductor memory device including a light emitting element, thereby stored information is electrically erased.
Heretofore, an EPROM has been widely employed as a memory device into which users can electrically write information. In order to rewrite information electrically, however, it is necessary to entirely erase the information by irradiating mainly ultraviolet rays. For this reason, in a semiconductor memory device such as an EPROM, as shown in FIG. 6 and FIG. 7 which is a sectional view taken along the line B--B of FIG. 6, a package comprising an opaque resin 1 has inconveniences that the package must be provided with a window 6 for the ultraviolet ray irradiation, that an expensive ceramic package must be prepared, and that the manufacture of the package requires a complex packaging process. Now, in FIG. 6 and FIG. 7 reference numeral 2 designates a lead wire; 3, a semiconductor chip; and 4, a wire such as a gold wire. Further, in order to irradiate ultraviolet rays to erase the information, there is a troublesome work that a semiconductor memory device having been once mounted on a printed board must be removed from the printed board. As a memory device instead of such an EPROM, there have been developed an electrically erasable and writable flash memory, an EEPROM and the like. However, due to a complexity in the structure of the semiconductor memory itself, such a high density memory as a flash memory or an EEPROM has not been manufactured at such low cost as an ultraviolet ray erasable EPROM.
As described above, the conventional ultraviolet ray erasable semiconductor memory has problems that the package must be provided with a window for the ultraviolet ray irradiation, and that in erasing information, the memory device must be removed from the printed board, subjected to the ultraviolet ray irradiation, and then must be mounted again onto the printed board.